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首页> 外文期刊>Atmospheric environment >First observations of light non-methane hydrocarbons (C-2-C-5) over a high altitude site in the central Himalayas
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First observations of light non-methane hydrocarbons (C-2-C-5) over a high altitude site in the central Himalayas

机译：在喜马拉雅山中部高海拔地区首次观测到的轻质非甲烷碳氢化合物（C-2-C-5）

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摘要

This study presents observations of methane (CH4) and light non-methane hydrocarbons (NMHCs) for the first time from a high altitude site Nainital (29.4 degrees N, 79.5 degrees E, 1958 m amsl) in the central Himalayas. The whole air samples collected with a frequency of 3 samples per week during April 2009-December 2011 are analyzed using a Gas Chromatograph equipped with Flame Ionization Detector (GC-FID). Additionally, samples were collected from two semi-urban sites (Haldwani and Pantnagar) in the adjoining Indo Gangetic plain region. CH4 and NMHCs show a distinct seasonal cycle over this region with more frequent observations of higher levels during winter (DJF) and late autumn (SON) and lower levels during the summer-monsoon (JJA). Different NMHCs exhibit better correlations during autumn/winter as compared to the summer-monsoon season. The annual mean mixing ratios of methane, ethane, ethene, propane, propene, i-butane, n-butane, acetylene, and i-pentane at Nainital are measured to be 1.9 +/- 0.1 ppmv, 1.8 +/- 1.0, 0.7 +/- 0.9, 0.6 +/- 0.8, 0.6 +/- 0.7, 0.6 +/- 0.7, 0.5 +/- 0.6, 1.0 +/- 0.8, and 0.5 +/- 0.6, respectively (all in ppbv). The seasonal cycle of CH4 at Nainital is found to be similar to other global high altitude sites (jungfraujoch and Mauna Loa) but somewhat different than a high altitude site Mt. Abu in India. NMHCs, other than ethane and propane, are found to be higher over this central Himalayan region than other sites. Additionally, composition of NMHCs is shown to be different over the study region when compared with other sites in the IGP region. A correlation study between ln((n-butane)/(ethane)) and In((i-butane)/(ethane)) showed that oxidation by the OH radical is the main removal mechanism of these species over the central Himalaya and dilution maintains the ratios of these species. The lowest slope of propane and acetylene with CO during summer and spring are indicating absence of fresh air mass over this region. This study fills a major gap in observational data for light NMHCs in the Himalayas and has implications for better understanding of tropospheric chemistry over this region. (C) 2015 Elsevier Ltd. All rights reserved.
机译：这项研究首次在喜马拉雅山中部的奈尼塔尔高空站点（北纬29.4度，东经79.5度，1958 m amsl）观察到了甲烷（CH4）和轻质非甲烷碳氢化合物（NMHCs）。使用配备有火焰离子化检测器（GC-FID）的气相色谱仪分析在2009年4月至2011年12月期间每周收集3次采样的全部空气样品。此外，还从毗邻的印度恒河平原地区的两个半城市站点（Haldwani和Pantnagar）采集了样本。 CH4和NMHCs在该地区表现出明显的季节性周期，更频繁地观察到冬季（DJF）和深秋（SON）的水平较高，而夏季季风（JJA）的水平较低。与夏季季风季节相比，不同的NMHC在秋季/冬季表现出更好的相关性。奈尼塔尔的甲烷，乙烷，乙烯，丙烷，丙烯，异丁烷，正丁烷，乙炔和异戊烷的年平均混合比经测量为1.9 +/- 0.1 ppmv，1.8 +/- 1.0、0.7分别为+/- 0.9、0.6 +/- 0.8、0.6 +/- 0.7、0.6 +/- 0.7、0.5 +/- 0.6、1.0 +/- 0.8和0.5 +/- 0.6（均以ppbv表示）。发现奈尼塔尔CH4的季节周期与其他全球高海拔站点（少女峰和莫纳洛阿）相似，但与高海拔站点Mt. 2有所不同。印度的阿布。在该喜马拉雅中部地区，除乙烷和丙烷外，NMHC的含量高于其他地区。此外，与IGP区域中的其他位点相比，研究区域中的NMHCs组成有所不同。 ln（（正丁烷）/（乙烷））和In（（异丁烷）/（乙烷））之间的相关性研究表明，OH自由基氧化是这些物种在喜马拉雅山中部和稀释区的主要去除机理保持这些物种的比例。夏季和春季，丙烷和乙炔与CO的最低斜率表明该区域没有新鲜空气。这项研究填补了喜马拉雅山轻型NMHC观测数据的主要空白，对更好地了解该地区对流层化学具有重要意义。 （C）2015 Elsevier Ltd.保留所有权利。

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  • 来源
    《Atmospheric environment》 |2016年第janaptab期|450-460|共11页
  • 作者

    Sarangi Tapaswini; Naja Manish; Lal S.; Venkataramani S.; Bhardwaj Piyush; Ojha N.; Kumar R.; Chandola H. C.;

  • 作者单位

    Aryabhatta Res Inst Observat Sci, Naini Tal, India|Kumaun Univ, Dept Phys, Naini Tal 263002, India;

    Aryabhatta Res Inst Observat Sci, Naini Tal, India;

    Phys Res Lab, Ahmadabad 380009, Gujarat, India;

    Phys Res Lab, Ahmadabad 380009, Gujarat, India;

    Aryabhatta Res Inst Observat Sci, Naini Tal, India;

    Aryabhatta Res Inst Observat Sci, Naini Tal, India;

    Aryabhatta Res Inst Observat Sci, Naini Tal, India|Natl Ctr Atmospher Res, Div Atmospher Chem, Boulder, CO 80307 USA;

    Kumaun Univ, Dept Phys, Naini Tal 263002, India;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    NMHCs; CH4; Central Himalaya; Regional pollution; IGP;

    机译：NMHC;CH4;喜马拉雅中部;区域污染;IGP;

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